By J. Kaelin. Milligan College.
Agglutination signifes the presence of individual cells or molecules 100mg aurogra mastercard, as in antibody excess order 100mg aurogra visa, or to some incomplete antibodies buy cheap aurogra 100 mg online. The minor part of the cross-match serum lipid or protein-induced nonspecifc inhibition reaction. It is of less importance than the major cross-match in the antibody excess zone of certain precipitation reactions. The A cross-reacting antibody is an antibody that reacts with prozone represents a false-negative reaction. When a serum epitopes on an antigen molecule different from the one that sample is believed to contain a certain antibody that is being stimulated its synthesis. The effect is attributable to shared masked or is demonstrating a prozone phenomenon, the sample epitopes on the two antigen molecules. A cross-reacting antigen is an antigen that interacts with an antibody synthesized following immunogenic challenge with Inhibition zone: See prozone. Epitopes shared between these two anti- gens or epitopes with a similar stereochemical confguration The prozone is that portion of the dilution range in which an may account for this type of cross-reactivity. The presence of immune serum of high agglutinin titer fails to agglutinate the the same or of a related epitope between bacterial cells, red homologues (Figure 8. Antigen–antibody reactions Cross-reactivity is the ability of an antibody or T-cell recep- are therefore surface phenomena. The antibody is the mirror tor to react with two or more antigens that share an epitope image of the antigen. Factors that affect the agglutination test are electrolytes, Cross-absorption is the use of cross-reacting antigens or pH, and temperature. Salt decreases the potential difference cross-reacting antibodies to absorb antibodies or antigens, between antigen particles and the surrounding liquid medium respectively. Agglutination occurs when the Dilution end point is a value expressed as the titer that refects potential drops below 15 mV. It is deter- increased the potential drops, favoring agglutination; but the mined by serial dilution of the antibody in serum or other body cohesive forces between particles also drops, which is unfavor- fuid while maintaining a constant amount of antigen. It is the precise dilution of serum reached following combination with all components needed for the With sera of high antibody titer, complete agglutination occurs reaction, i. This acid agglutination is nonspecifc, since even normal serum will End point is the greatest dilution of an antibody in solution agglutinate cells at this low pH. This type of nonspecifc agglu- that will still yield an identifable reaction when combined with tination is not antibody dependent. End-point immunoassay is a test in which the signal is mea- Above that temperature it is less rapid, and above 56°C the anti- sured as the antigen–antibody complex reaches equilibrium. In agglutination and precipitation reactions, the lack of agglutination or precipitation in tubes where the antibody Certain conditions must be established in the reacting medium concentration is greatest is known as a prozone or prozone for agglutination to take place. Optimally, agglutination reactions are carried out in neutral dilute salt solutions such as 0. This is attributable to suboptimal agglutination or precipitation The signifcance of ionic strength is demonstrated by agglu- in the region of antibody excess. Agglutination or precipitation tination without antibodies at neutral pH or by bacteria bear- becomes readily apparent in the tubes where the same anti- ing a negative surface charge following the addition of enough body is more dilute. Low salt concentra- to either blocking antibody or antibody combining with only tion below 10–3M NaCl, may prevent agglutination of bacteria Antigen–Antibody Interactions 305 Tube no. A negative surface charge of cells by counter ions to permit close similar phenomenon may take place in vivo when immune enough contact between cells for bivalent antibody molecules complexes form in the presence of excess antigen. Antigen antitoxins is evaluated by comparison with standard antitox- excess prevents lattice formation either in vitro or in vivo. Antitoxin combines with toxin Soluble complexes may produce tissue injury in vivo, which in varying proportions, depending on the ratio in which they is more severe if complement has been fxed. C5a attracts are combined, to form complexes which prove nontoxic when neutrophils, and there is increased capillary permeability. This means that toxins are polyva- body in the precipitin reaction leads to occupation of the lent. This phenomenon is explained by the ability of toxin to antigen-binding sites of all the antibody molecules and leaves combine with antitoxin in multiple proportions. Neutralization additional antigenic determinants free to combine with more does not destroy the reacting toxin. In many instances, toxin antibody molecules if excess antigen is added to the mixture. The effect of heat on a zootoxin is illustrated by the destruction Antigen of cobra venom antitoxin if cobra venom (toxin)–antivenom (antitoxin) mixtures are subjected to boiling. Since toxins have specifc affnities for certain tissues of the animal body, such as the high affnity of Ab Ag tetanus toxin for nervous tissue, antitoxins are believed to act by binding toxins before they have the opportunity to combine with specifc tissue cell receptors. Antibody Coulombic L+ dose (historical): The smallest amount of toxin which, forces when mixed with one unit of antitoxin and injected subcuta- figure 8. Role of positive and neously into a 250-g guinea pig, will kill the animal within 4 negative charges in agglutination of antigen by antibody. Clinically, immune hemolysis may toxin is that amount of toxin which focculates most rapidly be IgM mediated when immunoglobulins combine with with one unit of antitoxin in a series of mixtures containing red blood cell surfaces for which they are specifc, such as constant amounts of toxin and varying amounts of antitoxin. This results in the release of free hemoglobin in the intravascular space with serious consequences. By L focculating unit (historical):f The focculating unit of contrast, hemolysis mediated by IgG in the extravascular diphtheria toxin is that amount of toxin which focculates space may be less severe. There is an elevation of indirect most rapidly with one unit of antitoxin in a series of mixtures bilirubin, since the liver may not be able to conjugate the containing constant amounts of toxin and varying amounts bilirubin in case of massive hemolysis. Historically, a unit of antitoxin was considered tion of lactate dehydrogenase, and hemoglobin appears in as the least quantity that would neutralize 100 minimal the blood and urine. There is elevated urobilinogen in both lethal doses of toxin administered to a guinea pig. Hemolysis may be also attributable to the usage relates antitoxic activity to an international standard action of enzymes or other chemicals acting on the cell antitoxin. It can also be induced by such mechanisms as placing the red cells in a hypotonic solution. Lo dose (historical): This is the largest amount of toxin which, when mixed with one unit of antitoxin and injected Lysis is disruption of cells due to interruption of their cell subcutaneously into a 250-g guinea pig, will produce no membrane integrity. The microorganisms are frst rendered nonmotile, fol- result from the alteration of the immunoglobulin mol- lowed by complement-induced lysis in the presence of anti- ecules, such as that seen in rheumatoid arthritis, or may body. Immune bacteriolysis in vivo involving the cholera be produced locally, such as in type B hepatitis. Usually, more than one class of immuno- Hemolysis is caused by interruption of the cellular globulin may manifest a particular serological reactivity such integrity of red blood cells that may be either immune or as precipitation. The Thymus and T Lymphocytes 9 The thymus is a triangular bilobed structure enclosed in a The thymus develops from the branchial pouches of the phar- thin fbrous capsule and located retrosternally (Figure 9. In humans, the weight of the thymus culae into interconnecting lobules, and each lobule comprises at birth is 10 to 15 g. It continues to increase in size, reaching two histologically and functionally distinct areas, cortex and a maximum (30 to 40 g) at puberty. The cortex consists of a mesh of epi- with increasing age, but the adult gland is still functional.
It is be- ever 100 mg aurogra otc, the general aim in the acute situation is elimination of active ing diagnosed more frequently in developed countries as a result of suppuration purchase aurogra 100mg free shipping. Consideration of long-term efect on seizures is less tourism to countries where the disease is endemic  purchase aurogra 100mg with mastercard. Tus, despite the best eforts, even successfully treated brain ab- Neurocysticercosis is a helminthiasis caused by the encysted scesses can result in long-term neurological morbidity [174,175] larval stage, Cysticercus cellulosae, of the pork tapeworm Taenia and this is most frequently related to seizures, cognitive dysfunc- solium. In the frst stage, a human (the defnitive host) ingests un- tion and focal neurological defcit, with up to 50% of patients suf- dercooked pork containing viable cysticerci from within which the fering permanent neurological defcit . Te single most im- scolex hatches in the gut and attaches to the intestinal mucosa. Over portant factor infuencing mortality is the neurological condition 3 months, the tapeworm matures to a length of 2–7 m and gravid of the patient at the time of diagnosis . When humans become intermediate hosts by acci- Te reported incidence of epilepsy following brain abscess is be- dental ingestion of eggs (faecal–oral spread), the lifecycle is com- tween 30% and 80%. Postmortem studies of expatriates from endemic zones have operatively went on to develop late epilepsy. Te mean onset time improved our knowledge of natural human infection and it is now of seizures for patients in this group was 3. In fact 50% of patients in the older group solitary parenchymal lesion is the most common form and seizures had their frst seizure during the frst year afer diagnosis compared are the most common symptom, presenting in 70–90% of patients. Analysis of seizure frequency Lesions may be multiple and can cause signifcant mass efect, hy- showed that the maximum frequency occurred during the fourth drocephalus, basal arachnoiditis and cerebral infarction. Tis pattern of spontaneous resolu- gested that the risk of developing late seizures is related to the loca- tion has important implications for the correct diagnosis and treat- tion of the abscess. Tere is some evidence that there is a Diagnosis reduction in seizures among patients treated with aspiration as op- Torough history and neurological examination may yield clues, posed to excision [148,178]. Resective surgery of vascular and infective lesions for epilepsy 869 Seizures are the commonest symptom and may occur when a cyst Table 67. Other common presentations include symptoms of raised intracranial Absolute pressure. Calcifcations on plain X-rays of thigh Ten to twenty per cent of patients will have intraventricular cysts. Minor Tese may cause hydrocephalus and can be accompanied by nausea Subcutaneous nodules and vomiting, headache, ataxia and confusion. Focal neurological Clinical manifestations suggestive of cysticercosis defcits are uncommon. Cysts within the basal cisterns can present Disappearance of brain lesions with anticysticercal therapy with signs of meningeal irritation, hydrocephalus, vasculitis and stroke. Cysticercal encephalitis with mul- Household contact with Taenia solium infection tiple parenchymal infammatory cysts and difuse cerebral oedema has been described in young girls and such patients are at risk of se- Data from . It is visualized like a western blot, so Cerebral tuberculoma is the main diferential diagnosis and cri- that non-specifc bands can be ignored thereby ruling out crossre- teria for diferentiation are described by Rajshekar et al. Tuberculomas are, by contrast, A satisfactory international diagnostic protocol has yet to be usually irregular, solid, greater than 20 mm in size and present with agreed upon , although this has been addressed by a panel led a progressive defcit. Criteria are self-limiting condition whereas a tuberculoma is an active infection divided into categories based on the weight attached to each fea- that requires prolonged therapy with potentially toxic drugs. Te use of albendazole and praziquantel is not A study of 10 patients treated with praziquantel and albendazole recommended with single enhancing lesions because the cysticerci showed complete disappearance of 80% of fourth ventricular cysts. Of the other two cysts, one decreased signifcantly in size and the Good seizure control is usually achievable with a single lesion. Seven of these patients presented with epilepsy and sin- obstructive hydrocephalus, meningitis, encephalitis or spinal cord gle or multiple small enhancing parenchymal lesions and one with compression. Parenchymal cysts or calcifcations, or chronic men- hydrocephalus caused by a midbrain lesion. Tis conservative approach is since 1990 describe successful treatment of subarachnoid cysts with corroborated by other authors. Although surgery may still be indicated for sub- ment of 33 patients with large subarachnoid cysticercal cysts, for arachnoid cysts refractory to albendazole, anticysticercal therapy whom the usual recommendation would be surgical treatment. Some lesions, however, still of the patients in this series improved with albendazole and dexa- require surgical resection as frst-line treatment: cysts adjacent to methasone at 59-month follow-up. In most patients, improvement blood vessels and cranial nerves can cause an intense infammatory was rapid afer the initiation of treatment . Unnecessary and complex cysts within the Sylvian fssure may occlude the mid- surgery or therapy with potentially toxic drugs should be avoided. Skull base cysts should be treated surgical- ly if there is symptomatic brainstem compression. Te incidence of intracranial tuber- ciated with hydrocephalus and this should be treated before any culoma is decreasing, particularly in Western countries and this decision is made regarding the cyst . Tuberculoma should be distinguished Stool examination for proglottids Examine for subcutaneous nodules, fundoscopy from tuberculous meningitis although the two may coexist. Serological tests and intervals histopathology established tuberculosis as the cause. Diagnosis is further complicated by the fact that many patients Lesion persists with tuberculoma have no preceding history of tuberculosis infec- tion. In 1959, Obrador  showed that cerebral tuberculoma Management accounted for 20–40% of all intracranial masses. In 1972, the inci- Historically, tuberculomas were managed surgically, however the dence was put at 0. In 1987, a development of antituberculous chemotherapy has reversed this study in Saudi Arabia showed that tuberculoma constitutes approx- . Delay in defnitive treatment can be devastating: these were caused by cerebral tuberculoma . Because of their rarity, tuberculomas are if the diagnosis is likely, a trial of antituberculous therapy should not always considered in the diferential diagnosis of intracranial be begun without biopsy confrmation . Furthermore, the exact pathophysiology is still not clear, early open brain biopsy as soon as intracranial tuberculoma is sus- partly because of the impossibility of reproducing tuberculoma in pected, especially in rapidly progressing cases. Cerebral tuberculomas with coexistent ex- timetres in diameter and walled of by fbrous tissue. Diagnosis should be reviewed if the anticipat- and haemagglutination are acceptably sensitive and specifc; ed improvement in clinical condition and radiological appearance however, all are limited by crossreactivity with T. Furthermore, corticosteroids should be not sufcient on their own to establish the diagnosis . Hydatid bral abscess and cystic tumours such as metastasis, haemangioblas- (meaning ‘drop of water’) describes the fuid-flled cysts created by toma and glioma. Te adult abscesses and many neoplasms may produce perilesional oedema worm resides in the intestine and has a lifespan of approximately and also demonstrate signifcant contrast enhancement and a case 6 months. Sheep typically become intermediate hosts by ingesting report of solid cerebral Echinococcus mimicking primary brain tu- parasite ova in dog faeces. Arachnoid cysts are probably the intermediate hosts by ingesting parasite in dog faeces. On ingestion most difcult lesions to diferentiate from hydatid cysts; arachnoid of the ova, the larvae hatch and penetrate the intestinal mucosa.
Secretory that reproduce in the interstitial fuid aurogra 100mg without prescription, blood or lumens of the IgA is signifcant in preventing localized colonization aurogra 100mg low price, yet respiratory discount 100 mg aurogra visa, urogenital and gastrointestinal tracts rather than systemic antibodies protect from primary infection and sec- entering host cells. Mycoplasmas can evade the humoral immune response by undergoing anti- Invasive pathogens are pathogenic microorganisms that genic variation of surface antigens. T cells also appear to play successfully gains access to body even though defense mech- a role in immunity to mycoplasma, which needs to be further anisms are intact. It is antiphagocytic and facilitates viru- compared to the ratio of organism-specifc IgG in serum lence of streptococci. This is illustrated in the following formula: A protoplast is a bacterial cell from which the cell wall has been removed. It includes the cell protoplasm and the cyto- If the index is greater than 1, signifying a greater quantity plasmic membrane. The hypertonic solution protects them gests that the specifc organism of interest is producing an from lysis. Protoplasts can be produced from Gram-positive infection of the central nervous system. Similar indices can bacteria also by treatment with penicillin or other antibiot- be calculated for IgM and IgA antibody classes. Gram-negative bacteria have a cell wall comprised of a thin peptidoglycan A pathogen is an agent such as a microorganism that can layer enclosed by an exterior membrane of lipopolysaccha- produce disease through infection of the host. Protoplasts prepared from Gram-negative bacteria are frequently termed spheroplasts. They are natural or morphonuclear leukocytes infammatory responses leading to innate immune system receptors which recognize molecular the formation of pus at sites of infection. These receptors enhance natu- A pyogenic infection is infection associated with the gen- ral immune responses against microbes. Microorganisms that are well known for their macrophages that bind bacterial endotoxin to activate mac- pus-inducing or pyogenic potential include Streptococcal rophages, and the mannose receptor on phagocytes that bind pyogenes, Staphylococcus aureus, Streptococcus pneu- microbial glycoproteins or glycolipids, are examples of pattern moniae, and Hemophilus infuenzae. These plasma membrane or endocytic patients and those having defective phagocytic cell capac- vesicle membrane-bound pattern recognition molecules have ity show increased susceptibility to pyogenic infections. Pyogenic microorganisms stimulate a large polymorpho- Encapsulation is the reaction of leukocytes to foreign nuclear leukocyte response to their presence in tissues. Multiple layers of fattened leukocytes form a wall surround- Pyrogen is a substance that induces fever. This endogenously produced, such as interleukin-1 released from type of reaction occurs in invertebrates, including annelids, macrophages and monocytes, or it may be an endotoxin mollusks, and arthropods. Phagocyte reactive oxygen intermediates Phosphocholine antibodies are synthesized during selected and lysosomal enzymes then destroy the encapsulated patho- bacterial infections especially by Streptococcus (S), but also gens. In vertebrates, macrophages surround the foreign body, by Mycloplasma, Proteus, Trichinella, and Neisseria, in a granuloma is formed, and fbroblasts subsequently appear. This is believed to be Pili are structures that facilitate adhesion of bacteria to host associated with an immune response to lipopolysaccharide cells and are therefore direct determinants of virulence. Shigella may destroy antigen-presenting cells in the host following systemic exposure to Shigella antigens The Quellung phenomenon refers to the swelling of the and toxins before an immune response can be established. Previous Shigella infection leads to specifc IgA secretion in breast A Quellung reaction is the swelling of bacterial capsules milk. Antibodies develop early against somatic Shigella when the microorganisms are incubated with species-spe- antigens. Examples of bacteria in which this can be a single enzymatically active A subunit and 5B subunits observed include Streptococcus pneumoniae, Hemophilus needed for toxin binding. It is an important virulence factor tion of a drop of antiserum with a drop of material from a in the pathogenesis of hemolytic–uremic syndrome, which patient containing an encapsulated microorganism and the may be a complication of infection. The microorganisms are stained blue IgG can be raised against Shiga toxin in animal models. There may be some correlation between T cell acti- vation and the severity of the disease. Local cytokine synthe- Scarlet fever is a condition associated with production of sis is also signifcant in Shigellosis. There may be both a humoral and a not occur on the palms, the soles of the feet, or in the mouth. High-serum Patients may also develop Pastia’s lines, which are petechiae antitoxin titers failed to protect monkeys against intestinal in a linear pattern. Heat-killed Septic shock: Hypotension, with a systolic blood pressure of whole cell Shigella vaccines used in the past failed to give less than 90 mmHg or a decrease in the systolic pressure base- protection. Although mucosal secretory IgA is to prevent line of more than 40 mmHg, in individuals with sepsis. Vascular collapse, disseminated intravascular coag- ulation, and metabolic disorders occur. Vβ domain of selected T cell receptors, which qualifes staph- ylococcal enterotoxins to be classifed as superantigens. Serotyping has long been used to clas- sify Salmonella, streptococci, Shigella, and many other bac- Staphylococcus immunity: Most individuals synthesize teria. These antibodies are not protective Shigella immunity: The host protective immune response against staphylococcal infections. Since M cells of in diagnosis, but it is necessary to show a signifcant increase 736 Atlas of Immunology, Third Edition in antibody titer. It has been linked to the improper use of feminine enterotoxins, and exfoliatins are protective. The disease is by synthesizing IgG or IgM that interacts with capsular occurs 1 to 2 weeks after tetanus spores are introduced into polysaccharide which opsonizes the bacteria for ingestion deep wounds that provide anaerobic growth conditions. Most Tetanus toxin is the exotoxin synthesized by Clostridium individuals have low resistance as refected by their lack of tetani. It acts on the nervous system, interrupting neuromus- antibody to most of the commonly infecting pneumococcal cular transmission and preventing synaptic inhibition in the serotypes even though normal adults may have suffcient spinal cord. Treponema immunity: Infection with Treponema pallidum The complement fragments and bound Fc are inaccessible to induces both cellular and humoral immune responses. Vaccines to prevent streptococcal infections humoral response is characterized by the synthesis of both are hindered by the systemic local and systemic reactions phospholipid and treponemal antibodies that are detected in that follow administration of large does of M protein given the serological diagnosis of syphilis. This long been used to detect phospholipid or cardiolipin antibod- may be attributable to M proteins serving as superantigens. Cardiolipin F antibody specifc for host which has made possible immunization with purifed M pro- cell mitochondrial cardiolipin (autoantibody) is also associ- tein preparations to induce type-specifc opsonic antibodies ated with syphilis but is not used in diagnosis. Immunization antibodies that appear after infection together with car- protocols have also included attempts to stimulate antibod- diolipin antibodies are detectable by immunofuorescence. Autoantibodies against tissue phospholipids and other immunogenicity of this component. The cell-mediated immunity appears to be more important Streptococcal M protein is a cell-wall protein of virulent than the humoral response in the development of immunity.
Consequently cheap 100 mg aurogra free shipping, the sciatic nerve is at risk in a posterior surgical approach to the hip generic 100mg aurogra with visa, or in a posterior dislocation buy aurogra 100mg on line. The hip joint is innervated by the sciatic, femoral and obturator nerves (Hilton’s Law). In a child that presents with a painful knee, always examine the ipsilateral hip joint, in addition to examining the knee, to avoid missing a diseased hip. Most importantly, via retinacular vessels that run up from the trochanteric anastomosis and then along the neck of the femur to supply the major part of the head. The trochanteric anastomosis is formed by an anastomosis of the medial and lateral circumflex femoral arteries and the superior and inferior gluteal arteries. Via the nutrient, or diaphyseal, artery of the femur, originating from the second perforating artery of the profunda femoris artery. An intra-capsular fractured neck of the femur may disrupt the retinacular fibres and consequently disrupt the blood flow to the femoral head resulting in avascular necrosis. Garden 1 and 2 fractures are undisplaced fractures, whilst 3 and 4 are displaced fractures. The exception is the young patient with a 3 or 4 where the aim is to try and save the hip and therefore open reduction and internal fixation with cannulated screws is preferable in the first instance to avoid multiple hip revisions in the patient’s lifetime. The shoulder joint, like the hip joint, is a synovial joint of the ball and socket variety. Coracobrachialis Pectoralis minor Short head of biceps What important nerve lies in close proximity to the shoulder joint? It must never be forgotten that the axillary nerve lies in close proximity to the shoulder joint and the surgical neck of the humerus. Consequently, it is vulnerable to injury at the time of a shoulder dislocation, or whilst attempting to reduce the shoulder back into its normal position following a dislocation. It is therefore imperative (from both a clinical and medico-legal point of view) that the integrity of the axillary nerve is documented, both after seeing the patient who has a dislocated shoulder, but also following successful reduction. The knee joint is a synovial joint (the largest in the body), of the modified hinge variety. The cruciate ligaments are two very strong ligaments that cross each other within the joint cavity, but are excluded from the synovial cavity by a covering of synovial membrane (they are therefore described as being intra-capsular, but extra- synovial). Thus, the anterior cruciate ligament is attached to the anterior inter-condylar area of the tibia and runs upwards, backwards and laterally to attach itself to the medial surface of the lateral femoral condyle. Backward displacement of the tibia on the femur is prevented by the stronger posterior cruciate ligament which runs from the posterior part of the tibial inter- condylar area to the lateral aspect of the medial femoral condyle. The integrity of the latter is therefore important when walking down stairs or downhill. Tears of the anterior cruciate ligament are common in sports injuries; tears, however, of the posterior cruciate ligament are rare since it is much stronger than the anterior cruciate. Bursae are lubricating devices found wherever skin, muscle or tendon rubs against bone. An effusion of the knee may therefore extend some three to four finger breadths above the patella into the supra- patellar pouch. The pre-patellar and infra-patellar bursae do not communicate with the knee joint, but may become inflamed causing a painful bursitis. Inflammation of the pre-patellar bursa is known as housemaid’s knee, whereas that of the infra-patellar bursa is called clergyman’s knee. The menisci, or semilunar cartilages, are cresent-shaped laminae of fibrocartilage, the medial being larger and less curved than the lateral. Contributing to stability of the knee by their physical presence and by acting as providers of proprioceptive feedback 3. Probably assisting in lubrication The menisci are so effective that if they are removed, the force taken by the articular hyaline cartilage during peak loading increases by about five-fold. Meniscectomy (removal of the menisci), or damage to the menisci, therefore exposes the articular hyaline cartilage to much greater forces than normal and evidence of degenerative osteoarthritis is seen in 75% of patients 10 years after meniscectomy. The menisci are liable to injury from twisting strains applied to a flexed weight- bearing knee. The medial meniscus is much less mobile than the lateral meniscus (because of its strong attachment to the medial collateral ligament of the knee joint) and therefore cannot as easily accommodate abnormal stresses placed upon it. This, in part, explains why medial meniscal tears are more common than lateral meniscal tears. Upper lateral – Biceps femoris Upper medial – Semimembranosus and semitendinosus Lower lateral – Gastrocnemius (lateral head) and plantaris Lower medial – Gastrocnemius (medial head) Floor – Popliteus, capsule, femur Roof – Short saphenous and communicating veins, lateral sural cutaneous nerve, sural communicating nerve, end of posterior femoral cutaneous nerve and fascia lata Contents – Popliteal artery and vein (artery is deepest structure within the popliteal fossa and therefore the popliteal pulse is often difficult to palpate), tibial nerve, common fibular nerve, lymph nodes and fat Femoral triangle What are the boundaries of the femoral triangle? The boundaries of the femoral triangle are the inguinal ligament superiorly, the medial border of adductor longus medially and the medial border of sartorius laterally. The roof is fascia lata and the floor is made up of the following muscles: iliacus, psoas, pectineus and adductor longus. Within the femoral sheath lies the femoral artery, vein and a space most medially known as the femoral canal. The boundaries of the femoral canal are the femoral vein laterally, the lacunar ligament medially, the inguinal ligament anteriorly and the pectineal ligament posteriorly. Within the space of the femoral canal normally lies extra-peritoneal fat and a lymph node which is often given its eponymous name, Cloquet’s lymph node. Cloquet’s lymph node drains the lower limb, perineum and anterior abdominal wall inferior to the umbilicus. It may be enlarged (as inguinal lymphadenopathy) in cases of carcinoma and infection at these sites. The purpose of the femoral canal is to allow the laterally placed femoral vein to expand into it thereby encouraging venous return. However, a piece of bowel or omentum may extend down into the femoral space causing a femoral hernia. The femoral artery lies at the mid-inguinal point (half-way between the anterior superior iliac spine and symphysis pubis), not to be confused with the mid-point of the inguinal ligament (half-way between the anterior superior iliac spine and the pubic tubercle) which is the surface marking of the deep inguinal ring. This landmark can be used to assess the femoral pulse, but it also provides the clinician with a surface landmark for gaining access to the femoral artery for procedures such as coronary angioplasty and lower limb angiography and embolectomy. The adductor canal (also known as the subsartorial canal or Hunter’s canal) is an aponeurotic tunnel in the mid-third of the thigh extending from the apex of the femoral triangle proximally through to an opening in the adductor magnus distally (known as the adductor hiatus) to enter the popliteal fossa. Its boundaries are as follows: Roof – Sartorius and fascia Laterally – Vastus medialis Medially – Adductor longus (superiorly) and adductor magnus (inferiorly) Contents – Superficial femoral artery and femoral vein (latter deep to artery), saphenous nerve, nerve to vastus medialis (in upper part), small branch of posterior division of obturator nerve supplying knee joint, lymphatics Note that the saphenous nerve and the nerve to vastus medialis do not exit through the adductor hiatus. The femoral artery and vein become the popliteal artery and vein, respectively upon exiting the adductor hiatus. The adductor canal is anatomically narrow and is therefore a common site of turbulent blood flow leading to atherosclerosis. Two-thirds of the way along a line drawn from the anterior superior iliac spine to the adductor tubercle of the femur. Place your stethoscope at this point to auscultate for bruits in distal superficial femoral arterial disease in the claudicant patient since this is the commonest site of lower extremity peripheral vascular disease. In 10% of cases, the brachial plexus may be either pre-fixed (C4–C8) or post-fixed (C6–T2). The relation of the roots, trunks and divisions of the brachial plexus to the scalene muscles, first rib and clavicle are important. Compression within a fixed space (the thoracic outlet) may lead to symptoms resulting from compression of the brachial plexus and/or nearby vascular structures (subclavian artery and vein).
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